CA2445730A1 - Fiber optic fabry-perot interferometer and associated methods - Google Patents
Fiber optic fabry-perot interferometer and associated methods Download PDFInfo
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- CA2445730A1 CA2445730A1 CA002445730A CA2445730A CA2445730A1 CA 2445730 A1 CA2445730 A1 CA 2445730A1 CA 002445730 A CA002445730 A CA 002445730A CA 2445730 A CA2445730 A CA 2445730A CA 2445730 A1 CA2445730 A1 CA 2445730A1
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- 239000000835 fiber Substances 0.000 title claims abstract description 54
- 238000000034 method Methods 0.000 title claims abstract description 16
- 239000013307 optical fiber Substances 0.000 claims abstract description 60
- 239000000758 substrate Substances 0.000 claims abstract description 41
- 239000000853 adhesive Substances 0.000 claims abstract description 6
- 230000001070 adhesive effect Effects 0.000 claims abstract description 6
- 238000003486 chemical etching Methods 0.000 claims description 3
- 230000003287 optical effect Effects 0.000 description 13
- 239000000463 material Substances 0.000 description 5
- 230000005534 acoustic noise Effects 0.000 description 3
- 238000005253 cladding Methods 0.000 description 3
- 230000005855 radiation Effects 0.000 description 3
- 230000035939 shock Effects 0.000 description 3
- 238000005520 cutting process Methods 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 239000012790 adhesive layer Substances 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000010410 layer Substances 0.000 description 1
- 230000010363 phase shift Effects 0.000 description 1
Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
- G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
- G01J3/02—Details
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
- G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
- G01D5/26—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light
- G01D5/264—Mechanical constructional elements therefor ; Mechanical adjustment thereof
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
- G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
- G01D5/26—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light
- G01D5/266—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light by interferometric means
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
- G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
- G01D5/26—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light
- G01D5/268—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light using optical fibres
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
- G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
- G01J3/02—Details
- G01J3/0205—Optical elements not provided otherwise, e.g. optical manifolds, diffusers, windows
- G01J3/0218—Optical elements not provided otherwise, e.g. optical manifolds, diffusers, windows using optical fibers
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
- G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
- G01J3/12—Generating the spectrum; Monochromators
- G01J3/26—Generating the spectrum; Monochromators using multiple reflection, e.g. Fabry-Perot interferometer, variable interference filters
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
Abstract
The method for making the fiber optic Fabry-Perot sensor includes securing an optical fiber to a substrate, and forming at least one gap in the optical fiber after the optical fiber is secured to the substrate to define at least one pair of self-aligned opposing spaced apart optical fiber end faces for the Fabry-Perot sensor. Preferably, an adhesive directly secures the at least one pair of optical fiber portions to the substrate. The opposing spaced apart optical fiber end faces are self-aligned because the pair of optical fiber end portions are formed from a single fiber which has been directly secured to the substrate. Also, each of the self-aligned spaced apart optical fiber end faces may be substantially rounded due to an electrical discharge used to form the gap. This results in integral lenses being formed as the end faces of the fiber portions.
Description
G~~() FIBER OPTIC FABRY-PEROT INTERFEROMETER AND ASSOCIATED METHODS
Field of the Invention The present invention relates to optical sensors, and more particularly, to fiber optic fabry-perot interferometers.
Background of the Invention The Fabry-Perot Interferometer (FPI) is described by C.
Fabry and A. Perot in 1897 (Ann. Chem. Phys., 12:459-501) and is widely used in a variety of applications of optical systems. The basic structure and operation of the FPI sensor is well-known in the art and is described in many physics and optics texts. This interferometer includes an optical cavity formed between two typically reflecting, low-loss, partially transmitting mirrors.
The use of optical fibers allows for the manufacture of extremely compact and economic sensors known as Fiber-optic Fabry-Perot interferometric (FFPI) sensors. Ends of optical fiber portions form partially reflective surfaces with the cavity or gap therebetween. Changing the distance between optic fiber ends in the cavity or stretching an optical fiber in the cavity changes the intensity of the combined optical intensity due to interference. The sensor can be designed to sense, for example, acoustic noise, stress/strain, temperature, vibration, shock etc.
The fibers must be very accurately aligned and able to maintain that alignment during operation. This is typically an expensive and timely process that involves either an active alignment or a passive alignment. The active alignment typically includes launching light into one fiber while maximizing the light coupled into the second fiber. The fibers are aligned in three planes and at a plurality of angles. In a conventional passive alignment, fibers are inserted into a small microcapillary tube and glued in place.
These processes are also difficult to automate.
Thus, there is a need for a fiber optic Fabry-Perot interferometric sensor which is less expensive to produce.
The process of making the interferometer should be easily automated and involve a less timely alignment of the fibers.
Summnary of the Invention In view of the foregoing background, it is therefore a feature of the invention to provide a fiber optic Fabry-Perot interferometric sensor which is less expensive to produce via an easily automated and less timely process.
This and other features and advantages in accordance with the present invention are provided by a method for making a fiber optic Fabry-Perot sensor including securing an optical fiber to a substrate, and forming at least one gap in the optical fiber after the optical fiber is secured to the substrate to define at least one pair of self-aligned opposing spaced apart optical fiber end faces for the Fabry-Perot sensor. No alignment is needed because forming the gap in a single fiber which has been secured to the substrate results in the opposing end faces of the optical fiber portions being self-aligned.
The substrate preferably has a characteristic which is changeable, e.g. in response to a sensed condition. Also, the gap changes in response to changes in the characteristic of the substrate. Forming the gap may include forming the gap so that the at least one pair of spaced apart optical fiber end faces are substantially parallel. The substrate may be made of a material with a predetermined coefficient of thermal expansion, and may include a flexible material. The gap may be formed with an electrical discharge, by cleaving, or by chemical etching, for example. When cutting the fiber with an electrical discharge, the end faces of the remaining fiber portions adjacent the gap may be melted to form integral lenses.
The optical fiber is preferably a single mode optical fiber and includes an optical core, and may include a cladding surrounding the core. Furthermore, an optical source and an optical detector are preferably coupled to the optical fiber.
Also, the optical fiber is preferably secured to the substrate with an adhesive.
Features and advantages in accordance with the present invention are also provided by a fiber optic Fabry-Perot sensor including a substrate having a characteristic which is changeable, and at least one pair of optical fiber portions aligned in end-to-end relation and defining a gap between at Least one pair of self-aligned opposing spaced apart optical fiber end faces. Preferably, an adhesive directly secures the at least one pair of optical fiber portions to the substrate.
The opposing spaced apart optical fiber end faces are self-aligned because the pair of optical fiber end portions are formed from a single fiber which preferably has been directly secured to the substrate. Also, each of the self-aligned spaced apart optical fiber end faces may be substantially rounded due to an electrical discharge used to form the gap.
This results in integral lenses being formed as the end faces of the fiber portions.
Again, the gap changes in response to changes in the characteristic of the substrate, and the substrate may include at least one flat surface to which the at least one pair of optical fiber portions are secured thereto. Each of the self-aligned spaced apart optical fiber end faces may be substantially parallel, and the substrate may be formed of a flexible material. Also, each of the optical fiber portions may comprise a single mode optical fiber, or at least one of the fiber portions may be multimode.
Brief Description of the Drawings FIG. 1 is schematic diagram of a fiber-optic Fabry-Perot interferometric (FFPI) sensor system in accordance with the present invention.
FIG. 2 is a cross-sectional view of a sensor of the FFPI
sensor system of FIG. 1.
Field of the Invention The present invention relates to optical sensors, and more particularly, to fiber optic fabry-perot interferometers.
Background of the Invention The Fabry-Perot Interferometer (FPI) is described by C.
Fabry and A. Perot in 1897 (Ann. Chem. Phys., 12:459-501) and is widely used in a variety of applications of optical systems. The basic structure and operation of the FPI sensor is well-known in the art and is described in many physics and optics texts. This interferometer includes an optical cavity formed between two typically reflecting, low-loss, partially transmitting mirrors.
The use of optical fibers allows for the manufacture of extremely compact and economic sensors known as Fiber-optic Fabry-Perot interferometric (FFPI) sensors. Ends of optical fiber portions form partially reflective surfaces with the cavity or gap therebetween. Changing the distance between optic fiber ends in the cavity or stretching an optical fiber in the cavity changes the intensity of the combined optical intensity due to interference. The sensor can be designed to sense, for example, acoustic noise, stress/strain, temperature, vibration, shock etc.
The fibers must be very accurately aligned and able to maintain that alignment during operation. This is typically an expensive and timely process that involves either an active alignment or a passive alignment. The active alignment typically includes launching light into one fiber while maximizing the light coupled into the second fiber. The fibers are aligned in three planes and at a plurality of angles. In a conventional passive alignment, fibers are inserted into a small microcapillary tube and glued in place.
These processes are also difficult to automate.
Thus, there is a need for a fiber optic Fabry-Perot interferometric sensor which is less expensive to produce.
The process of making the interferometer should be easily automated and involve a less timely alignment of the fibers.
Summnary of the Invention In view of the foregoing background, it is therefore a feature of the invention to provide a fiber optic Fabry-Perot interferometric sensor which is less expensive to produce via an easily automated and less timely process.
This and other features and advantages in accordance with the present invention are provided by a method for making a fiber optic Fabry-Perot sensor including securing an optical fiber to a substrate, and forming at least one gap in the optical fiber after the optical fiber is secured to the substrate to define at least one pair of self-aligned opposing spaced apart optical fiber end faces for the Fabry-Perot sensor. No alignment is needed because forming the gap in a single fiber which has been secured to the substrate results in the opposing end faces of the optical fiber portions being self-aligned.
The substrate preferably has a characteristic which is changeable, e.g. in response to a sensed condition. Also, the gap changes in response to changes in the characteristic of the substrate. Forming the gap may include forming the gap so that the at least one pair of spaced apart optical fiber end faces are substantially parallel. The substrate may be made of a material with a predetermined coefficient of thermal expansion, and may include a flexible material. The gap may be formed with an electrical discharge, by cleaving, or by chemical etching, for example. When cutting the fiber with an electrical discharge, the end faces of the remaining fiber portions adjacent the gap may be melted to form integral lenses.
The optical fiber is preferably a single mode optical fiber and includes an optical core, and may include a cladding surrounding the core. Furthermore, an optical source and an optical detector are preferably coupled to the optical fiber.
Also, the optical fiber is preferably secured to the substrate with an adhesive.
Features and advantages in accordance with the present invention are also provided by a fiber optic Fabry-Perot sensor including a substrate having a characteristic which is changeable, and at least one pair of optical fiber portions aligned in end-to-end relation and defining a gap between at Least one pair of self-aligned opposing spaced apart optical fiber end faces. Preferably, an adhesive directly secures the at least one pair of optical fiber portions to the substrate.
The opposing spaced apart optical fiber end faces are self-aligned because the pair of optical fiber end portions are formed from a single fiber which preferably has been directly secured to the substrate. Also, each of the self-aligned spaced apart optical fiber end faces may be substantially rounded due to an electrical discharge used to form the gap.
This results in integral lenses being formed as the end faces of the fiber portions.
Again, the gap changes in response to changes in the characteristic of the substrate, and the substrate may include at least one flat surface to which the at least one pair of optical fiber portions are secured thereto. Each of the self-aligned spaced apart optical fiber end faces may be substantially parallel, and the substrate may be formed of a flexible material. Also, each of the optical fiber portions may comprise a single mode optical fiber, or at least one of the fiber portions may be multimode.
Brief Description of the Drawings FIG. 1 is schematic diagram of a fiber-optic Fabry-Perot interferometric (FFPI) sensor system in accordance with the present invention.
FIG. 2 is a cross-sectional view of a sensor of the FFPI
sensor system of FIG. 1.
FIGs. 3-5 are cross-sectional views illustrating various steps in making the sensor of FIG. 2.
FIG. 6 is a cross-sectional view illustrating an alternative embodiment of the sensor of FIG. 2.
Detailed Description of the Preferred Embodiments The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.
Like numbers refer to like elements throughout. The dimensions of layers and regions may be exaggerated in the figures for clarity.
Referring to FIGS. 1 and 2, a fiber-optic Fabry-Perot interferometric (FFPI) sensor system 10 will now be described.
The system 10 includes a control and signal processor 12 coupled to a FFPI sensor 14 via fiber optic cable 26. The sensor 14 can be located kilometers away from the processor 12, and requires no electrical power. The processor 12 includes light source 16, such as a laser diode. Radiation or light from the light source 16 is coupled to the fiber 18 and propagates through the coupler 20 to the fiber 26. At the sensor 14, some radiation is reflected back into the fiber 26 through the coupler 20 and into the optical detector 22, as will be explained in detail below. The fibers 18, 24 and 26 are preferably single mode fibers as would be readily appreciated by the skilled artisan.
As previously discussed, a typical interferometer includes an optical cavity formed between two typically reflecting, low-loss, partially transmitting mirrors. Lenses are typically used to collimate divergent optical beams.
FIG. 6 is a cross-sectional view illustrating an alternative embodiment of the sensor of FIG. 2.
Detailed Description of the Preferred Embodiments The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.
Like numbers refer to like elements throughout. The dimensions of layers and regions may be exaggerated in the figures for clarity.
Referring to FIGS. 1 and 2, a fiber-optic Fabry-Perot interferometric (FFPI) sensor system 10 will now be described.
The system 10 includes a control and signal processor 12 coupled to a FFPI sensor 14 via fiber optic cable 26. The sensor 14 can be located kilometers away from the processor 12, and requires no electrical power. The processor 12 includes light source 16, such as a laser diode. Radiation or light from the light source 16 is coupled to the fiber 18 and propagates through the coupler 20 to the fiber 26. At the sensor 14, some radiation is reflected back into the fiber 26 through the coupler 20 and into the optical detector 22, as will be explained in detail below. The fibers 18, 24 and 26 are preferably single mode fibers as would be readily appreciated by the skilled artisan.
As previously discussed, a typical interferometer includes an optical cavity formed between two typically reflecting, low-loss, partially transmitting mirrors. Lenses are typically used to collimate divergent optical beams.
Fiber-optic Fabry-Perot interferometric (FFPI) sensors are extremely compact and economic because of the use of optical fibers. Ends of optical fiber portions form partially reflective surfaces with the cavity or gap therebetween.
Changing the distance between optic fiber ends in the cavity or stretching an optical fiber in the cavity changes the intensity of the optical radiation. The sensor can be designed to sense, for example, acoustic noise, stress/strain, temperature, vibration, shock etc.
The fibers must be very accurately aligned and able to maintain that alignment during operation. Conventionally, this is an expensive and timely process that involves aligning the fibers in three planes and at a plurality of angles. In a conventional passive alignment, fibers are inserted into a small microcapillary tube and glued in place. Both of these processes are also difficult to automate. The sensor 14 of the present invention does not need any alignment process because the resulting opposing fiber portions are automatically self-aligned.
The sensor 14 will be described in greater detail with reference to FIG. 2. The sensor 14 includes a structure or substrate 30 having a characteristic which is changeable. For example, the substrate 30 may be a flexible substrate. The sensor 14 also includes a pair of optical fiber portions 32, 34 aligned in end-to-end relation. A gap 42 is defined by the pair of self-aligned opposing spaced apart optical fiber end faces 38 and 40. The end faces form partially reflective surfaces for the Fabry-Perot sensor 14. Preferably, an adhesive 36 directly secures the optical fiber portions 32, 34 to the substrate 30. Each of the optical fiber portions 32, 34 may comprise a single mode optical fiber having a core 33 surrounded by cladding 35. Of course the sensor 14 may also include multiple gaps defined by three more fiber portions as would be appreciated by the skilled artisan.
Changing the distance between optic fiber ends in the cavity or stretching an optical fiber in the cavity changes the intensity of the optical radiation. The sensor can be designed to sense, for example, acoustic noise, stress/strain, temperature, vibration, shock etc.
The fibers must be very accurately aligned and able to maintain that alignment during operation. Conventionally, this is an expensive and timely process that involves aligning the fibers in three planes and at a plurality of angles. In a conventional passive alignment, fibers are inserted into a small microcapillary tube and glued in place. Both of these processes are also difficult to automate. The sensor 14 of the present invention does not need any alignment process because the resulting opposing fiber portions are automatically self-aligned.
The sensor 14 will be described in greater detail with reference to FIG. 2. The sensor 14 includes a structure or substrate 30 having a characteristic which is changeable. For example, the substrate 30 may be a flexible substrate. The sensor 14 also includes a pair of optical fiber portions 32, 34 aligned in end-to-end relation. A gap 42 is defined by the pair of self-aligned opposing spaced apart optical fiber end faces 38 and 40. The end faces form partially reflective surfaces for the Fabry-Perot sensor 14. Preferably, an adhesive 36 directly secures the optical fiber portions 32, 34 to the substrate 30. Each of the optical fiber portions 32, 34 may comprise a single mode optical fiber having a core 33 surrounded by cladding 35. Of course the sensor 14 may also include multiple gaps defined by three more fiber portions as would be appreciated by the skilled artisan.
The opposing spaced apart optical fiber end faces 38, 40 are self-aligned because the pair of optical fiber end portions 32, 34 are formed from a single fiber which preferably has been directly secured to the substrate 30 as will be further described below. In an alternative embodiment, as illustrated in FIG. 6, each of the self-aligned spaced apart optical fiber end faces 38', 40' may be substantially rounded due to an electrical discharge used to form the gap as will also be described below. The lenses collimate divergent optical beams for processing through the sensor 14.
As discussed, the gap 42 changes in response to changes in the characteristic of the substrate 30. The substrate 30 may include at least one flat surface 37 to which the at least 15 one pair of optical fiber portions 32, 34 are secured thereto.
Each of the self-aligned spaced apart optical fiber end faces 38, 40 may be substantially parallel.
When laser light is guided into the sensor 14 via the light source 16 and coupler 20, a portion of the light is reflected by each of the partially reflective end faces 38, 40 generating an interference effect. The interference is created constructively (reflections in phase) or destructively (reflections out of phase). When reflections are in phase, the reflected output is at a maximum. When reflections are out of phase, the reflected output is at a minimum. The phase shift is a result of changes in the length of the gap 42 or cavity with respect to the wavelength of Light.
If the input beam from the light source 16 passes from the fiber portion 32 to fiber portion 34, then the reflection from the reflective end face 38 back into the fiber portion 32 may be referred to as the reference beam. Likewise, the reflection from the end face 40 back across the gap 42 and into the fiber portion 32 may be referred to as the signal beam. The intensity (I) of the combined signal and reference beams is a function of the phase modulation in the gap 42.
Thus, nanometer scale changes in the gap 42 length L can be detected.
A method of making the sensor 14 will now be described with reference to FIGS. 3-5. First, an optical fiber 31 is secured to the substrate 30, for example, by an adhesive layer 36. The optical fiber is typically, but not necessarily, a single mode fiber and typically includes a core 33 surrounded by cladding 35. The fiber 31 is preferably secured to the substrate with an adhesive as would be appreciated by the skilled artisan. As can be seen in FIGS. 4 and 5, a gap 42 is formed in the optical fiber 31 after the optical fiber is secured to the substrate 30. The gap may be formed with an electrical discharge 44, by cleaving, or by chemical etching, for example.
A pair of fiber portions 32, 34 are created from the fiber 31, and a pair of spaced apart optical fiber end faces 38, 40 oppose each other with the gap 42 therebetween. The end faces 38, 40 form the partially reflective surfaces for the Fabry-Perot sensor 14. Moreover, the fiber portions 32, 34 and the respective end faces 38, 40 are inherently aligned or self-aligned due to the gap 42 being formed in a single fiber 31 which has been secured to the substrate 30. Thus, no active alignment or the use of a microcapillary tube is necessary.
The substrate 30 preferably has a characteristic which is changeable, e.g. in response to a sensed condition such as, for example, acoustic noise, stress/strain, temperature, vibration, pressure, flow, shock etc., as would be appreciated by those skilled in the art. The substrate 30 may be made of a material with a predetermined coefficient of thermal expansion, and may include a flexible material. Also, the length of the gap 42 changes in response to changes in the characteristic of the substrate 30. Forming the gap 42 may include forming the gap so that the at least one pair of spaced apart optical fiber end faces 38, 40 are substantially parallel.
When cutting the fiber 31 with an electrical discharge 5 44, the end faces 38', 40' of the remaining fiber portions 32, 34 adjacent the gap 42 may be melted to form integral lenses, as can be seen in FIG. 6. The lenses collimate divergent optical beams for processing through the sensor 14.
_g_
As discussed, the gap 42 changes in response to changes in the characteristic of the substrate 30. The substrate 30 may include at least one flat surface 37 to which the at least 15 one pair of optical fiber portions 32, 34 are secured thereto.
Each of the self-aligned spaced apart optical fiber end faces 38, 40 may be substantially parallel.
When laser light is guided into the sensor 14 via the light source 16 and coupler 20, a portion of the light is reflected by each of the partially reflective end faces 38, 40 generating an interference effect. The interference is created constructively (reflections in phase) or destructively (reflections out of phase). When reflections are in phase, the reflected output is at a maximum. When reflections are out of phase, the reflected output is at a minimum. The phase shift is a result of changes in the length of the gap 42 or cavity with respect to the wavelength of Light.
If the input beam from the light source 16 passes from the fiber portion 32 to fiber portion 34, then the reflection from the reflective end face 38 back into the fiber portion 32 may be referred to as the reference beam. Likewise, the reflection from the end face 40 back across the gap 42 and into the fiber portion 32 may be referred to as the signal beam. The intensity (I) of the combined signal and reference beams is a function of the phase modulation in the gap 42.
Thus, nanometer scale changes in the gap 42 length L can be detected.
A method of making the sensor 14 will now be described with reference to FIGS. 3-5. First, an optical fiber 31 is secured to the substrate 30, for example, by an adhesive layer 36. The optical fiber is typically, but not necessarily, a single mode fiber and typically includes a core 33 surrounded by cladding 35. The fiber 31 is preferably secured to the substrate with an adhesive as would be appreciated by the skilled artisan. As can be seen in FIGS. 4 and 5, a gap 42 is formed in the optical fiber 31 after the optical fiber is secured to the substrate 30. The gap may be formed with an electrical discharge 44, by cleaving, or by chemical etching, for example.
A pair of fiber portions 32, 34 are created from the fiber 31, and a pair of spaced apart optical fiber end faces 38, 40 oppose each other with the gap 42 therebetween. The end faces 38, 40 form the partially reflective surfaces for the Fabry-Perot sensor 14. Moreover, the fiber portions 32, 34 and the respective end faces 38, 40 are inherently aligned or self-aligned due to the gap 42 being formed in a single fiber 31 which has been secured to the substrate 30. Thus, no active alignment or the use of a microcapillary tube is necessary.
The substrate 30 preferably has a characteristic which is changeable, e.g. in response to a sensed condition such as, for example, acoustic noise, stress/strain, temperature, vibration, pressure, flow, shock etc., as would be appreciated by those skilled in the art. The substrate 30 may be made of a material with a predetermined coefficient of thermal expansion, and may include a flexible material. Also, the length of the gap 42 changes in response to changes in the characteristic of the substrate 30. Forming the gap 42 may include forming the gap so that the at least one pair of spaced apart optical fiber end faces 38, 40 are substantially parallel.
When cutting the fiber 31 with an electrical discharge 5 44, the end faces 38', 40' of the remaining fiber portions 32, 34 adjacent the gap 42 may be melted to form integral lenses, as can be seen in FIG. 6. The lenses collimate divergent optical beams for processing through the sensor 14.
_g_
Claims (10)
1. A method for making a fiber optic Fabry-Perot interferometer comprising:
securing an optical fiber to a substrate; and forming at least one gap in the optical fiber after the optical fiber is secured to the substrate to define at least one pair of self-aligned opposing spaced apart optical fiber end faces for the Fabry-Perot interferometer.
securing an optical fiber to a substrate; and forming at least one gap in the optical fiber after the optical fiber is secured to the substrate to define at least one pair of self-aligned opposing spaced apart optical fiber end faces for the Fabry-Perot interferometer.
2. A method according to Claim 1 wherein the substrate comprises a flexible substrate.
3. A method according to Claim 1 wherein forming the at least one gap comprises forming the at least one gap using an electrical discharge.
4. A method according to Claim 1 wherein forming the at least one gap comprises forming the at least one gap by cleaving.
5. A method according to Claim 1 wherein forming the at least one gap comprises forming the at least one gap by chemical etching.
6. A fiber optic Fabry-Perot interferometer comprising:
a substrate having a characteristic which is changeable;
at least one pair of optical fiber portions aligned in end-to-end relation and defining a gap between at least one pair of self-aligned opposing spaced apart optical fiber end faces, and wherein the at least one gap changes in response to changes in the characteristic of the substrate; and an adhesive directly securing the at least one pair of optical fiber portions to the substrate.
a substrate having a characteristic which is changeable;
at least one pair of optical fiber portions aligned in end-to-end relation and defining a gap between at least one pair of self-aligned opposing spaced apart optical fiber end faces, and wherein the at least one gap changes in response to changes in the characteristic of the substrate; and an adhesive directly securing the at least one pair of optical fiber portions to the substrate.
7. A fiber optic Fabry-Perot sensor according to Claim 6 wherein the substrate comprises at least one flat surface to which the at least one pair of optical fiber portions are secured thereto.
8. A fiber optic Fabry-Perot sensor according to Claim 6 wherein each of the self-aligned spaced apart optical fiber end faces is substantially parallel.
9. A fiber optic Fabry-Perot sensor according to Claim 6 wherein each of the self-aligned spaced apart optical fiber end faces is substantially rounded and comprises an integral lens.
10. A fiber optic Fabry-Perot sensor according to Claim 6 wherein the substrate comprises a flexible substrate.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US10/287,192 US6886365B2 (en) | 2002-11-04 | 2002-11-04 | Fiber optic Fabry-Perot interferometer and associated methods |
| US10/287,192 | 2002-11-04 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2445730A1 true CA2445730A1 (en) | 2004-05-04 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
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| CA002445730A Abandoned CA2445730A1 (en) | 2002-11-04 | 2003-10-07 | Fiber optic fabry-perot interferometer and associated methods |
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| US (1) | US6886365B2 (en) |
| EP (1) | EP1416246B1 (en) |
| JP (1) | JP2004157533A (en) |
| AU (1) | AU2003252876A1 (en) |
| CA (1) | CA2445730A1 (en) |
| DE (1) | DE60311048T2 (en) |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7492463B2 (en) | 2004-04-15 | 2009-02-17 | Davidson Instruments Inc. | Method and apparatus for continuous readout of Fabry-Perot fiber optic sensor |
| US7623218B2 (en) | 2004-11-24 | 2009-11-24 | Carl Zeiss Smt Ag | Method of manufacturing a miniaturized device |
| EP1674833A3 (en) | 2004-12-21 | 2007-05-30 | Davidson Instruments, Inc. | Fiber optic sensor system |
| EP1681540A1 (en) * | 2004-12-21 | 2006-07-19 | Davidson Instruments, Inc. | Multi-channel array processor |
| US20060274323A1 (en) * | 2005-03-16 | 2006-12-07 | Gibler William N | High intensity fabry-perot sensor |
| US8432552B2 (en) * | 2005-03-16 | 2013-04-30 | Halliburton Energy Services, Inc. | High intensity Fabry-Perot sensor |
| WO2007033069A2 (en) * | 2005-09-13 | 2007-03-22 | Davidson Instruments Inc. | Tracking algorithm for linear array signal processor for fabry-perot cross-correlation pattern and method of using same |
| US20070147738A1 (en) * | 2005-12-12 | 2007-06-28 | Xingwei Wang | Intrinsic fabry-perot structure with micrometric tip |
| DE102006002605B4 (en) | 2006-01-13 | 2018-09-13 | Hans Joachim Eichler | Optical module with an optical fiber and a Fabry-Perot layer structure as electro-optical modulator and tunable filter |
| US7684051B2 (en) | 2006-04-18 | 2010-03-23 | Halliburton Energy Services, Inc. | Fiber optic seismic sensor based on MEMS cantilever |
| EP2021747B1 (en) | 2006-04-26 | 2018-08-01 | Halliburton Energy Services, Inc. | Fiber optic mems seismic sensor with mass supported by hinged beams |
| US8115937B2 (en) * | 2006-08-16 | 2012-02-14 | Davidson Instruments | Methods and apparatus for measuring multiple Fabry-Perot gaps |
| CA2676246C (en) * | 2007-01-24 | 2013-03-19 | Halliburton Energy Services, Inc. | Transducer for measuring environmental parameters |
| US8125646B2 (en) * | 2007-03-08 | 2012-02-28 | Davidson Instruments Inc. | Apparatus and methods for monitoring combustion dynamics in a gas turbine engine |
| US7602198B2 (en) * | 2007-10-19 | 2009-10-13 | Dynamp, Llc | Accuracy enhancing mechanism and method for current measuring apparatus |
| DE102008054915A1 (en) * | 2008-12-18 | 2010-06-24 | Endress + Hauser Flowtec Ag | Measuring device with an optical sensor |
| US9528893B2 (en) | 2009-06-29 | 2016-12-27 | University Of Massachusetts | Optical fiber pressure sensor with uniform diaphragm and method of fabricating same |
| DE102009035386B4 (en) * | 2009-07-30 | 2011-12-15 | Cochlear Ltd. | Hörhilfeimplantat |
| US8427652B2 (en) * | 2010-01-07 | 2013-04-23 | Harris Corporation | Systems and methods for measuring geometric changes of embedded passive materials during a lamination process |
| EP2675361A4 (en) | 2011-02-17 | 2016-09-14 | Univ Massachusetts | Photoacoustic probe |
| TWI563304B (en) * | 2012-05-22 | 2016-12-21 | Hon Hai Prec Ind Co Ltd | Laser signal transmitting device |
| CN104062569B (en) * | 2014-07-08 | 2017-04-05 | 国家电网公司 | A kind of shelf depreciation direction detection method of compound eye type optical fiber EFPI |
| US9437911B1 (en) * | 2015-05-21 | 2016-09-06 | Harris Corporation | Compliant high speed interconnects |
| DE102015210215A1 (en) | 2015-06-02 | 2016-12-08 | Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. | An optical filter, optical device and method for determining a property of a substance using such an optical filter |
| GB202009964D0 (en) * | 2020-06-30 | 2020-08-12 | Ams Int Ag | Spectral sensor |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4444460A (en) | 1981-05-26 | 1984-04-24 | Gould Inc. | Optical fiber apparatus including subtstrate ruggedized optical fibers |
| US4830451A (en) | 1986-03-05 | 1989-05-16 | American Telephone And Telegraph Company | Technique and apparatus for fabricating a fiber Fabry-Perot etalon |
| DE3929453C1 (en) | 1989-09-05 | 1991-03-21 | Messerschmitt-Boelkow-Blohm Gmbh, 8012 Ottobrunn, De | Fibre-Fabry-Perot interferometer - has slot in substrate enabling opposite regions to be moved w.r.t. V=shaped groove for optical fibres |
| US5714680A (en) | 1993-11-04 | 1998-02-03 | The Texas A&M University System | Method and apparatus for measuring pressure with fiber optics |
| US5528367A (en) * | 1994-09-09 | 1996-06-18 | The United States Of America As Represented By The Secretary Of The Navy | In-line fiber etalon strain sensor |
| US5682237A (en) | 1995-05-26 | 1997-10-28 | McDonnell Douglas | Fiber strain sensor and system including one intrinsic and one extrinsic fabry-perot interferometer |
| US6445838B1 (en) * | 2000-09-29 | 2002-09-03 | Corning Incorporated | Tunable optical component |
-
2002
- 2002-11-04 US US10/287,192 patent/US6886365B2/en not_active Expired - Fee Related
-
2003
- 2003-10-07 CA CA002445730A patent/CA2445730A1/en not_active Abandoned
- 2003-10-08 AU AU2003252876A patent/AU2003252876A1/en not_active Abandoned
- 2003-10-22 JP JP2003362140A patent/JP2004157533A/en active Pending
- 2003-11-04 EP EP03025362A patent/EP1416246B1/en not_active Expired - Fee Related
- 2003-11-04 DE DE60311048T patent/DE60311048T2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| DE60311048T2 (en) | 2007-05-31 |
| EP1416246A3 (en) | 2004-12-29 |
| US6886365B2 (en) | 2005-05-03 |
| AU2003252876A1 (en) | 2004-05-20 |
| EP1416246A2 (en) | 2004-05-06 |
| DE60311048D1 (en) | 2007-02-22 |
| JP2004157533A (en) | 2004-06-03 |
| US20040086228A1 (en) | 2004-05-06 |
| EP1416246B1 (en) | 2007-01-10 |
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| EEER | Examination request | ||
| FZDE | Discontinued |